Enzymes are catalysts that are produced by livingcells.
An enzyme is a protein molecule.

Enzymes are
very specificcatalysts. This means that
one particularenzyme will act as acatalyst for one
particularreaction but nothing else.

What are the OptimumConditions for an Enzyme?

An enzyme will work best at a particular temperature and pH,
called its optimumconditions.
Enzymes usually work
best in warmconditions (around 35
to 40 °C) unlike chemicalcatalysts
which often work best when they are very hot.

What is Enzyme Activity?

Enzyme activity is a
measure of how well (how efficiently)
an enzyme works as a catalyst. A graph ofenzyme activity plotted against temperature
is shown below.

The enzyme
in the graph above works most efficiently as
a catalyst at 40 °C
. This is the optimumtemperaturefor this enzyme. Above 40
°C the enzyme begins to work
less efficiently as a catalyst because the
shape of theenzyme molecule starts to change and it is said to denature.

A
graph of enzyme activity
against pH would have
a similar shape
but the peak (the optimumconditions)
would be at a differentpH for differentenzymes.

Pepsin in the stomach
works best at pH = 2.Amylase in the mouth works best at pH = 7.